just lately on my ba 4.0 when I install an edited tune file from sct xcal 3 the ECU accepts the changes as it should & it will drive perfectly all day with the new tune file installed until I turn off the key. But the problem is that the ECU is only keeping the new Tune settings for a short time. (until the next start-up). Soon as I restart all of the new tune settings are gone.

For some reason the ECU adaptive memory is reverting all the new tune settings back to how they were in the previous tune file.Maybe I should revert back to the old school way of doing things by Flashing the ECU & then disconnecting the battery trick to clear the adaptive memory.

I don't believe it. Can you read the tune back out the day after and compare the file to conclusively say it is reverting the tune?

Sounds more like a problem with your injector slopes. If you put in the wrong figures it will tend to drive in open loop fine (despite being rich/lean) but the next day when the long term fuel trims start to learn around the conditions you can cause it to fight.

Eg if you are lean at idle but rich at 1000 rpm due to wrong injector slopes the ECU will end up learning rich and then lean for the same MAP point. This will cause the O2 to self correct constantly and you end up with an oscillating rich/lean which causes all sorts of issues. You can test if this is the issue by unplugging the O2 sensor and writing the tune, this will disable all long term fuel trims.

The adaptive memory is only long/short term fuel trims afaik and these are only active in closed loop (low throttle, low rpm), the actual maps are hard coded and will not change.

OK, that sounds right to me too but to be more specific, my Tuner changed the Rev limit in Neutral/Park to a lower setting than is listed on the xCal3 settings (2300 rpm). The xCal3 only goes as low as 2500.This was changed because at start-up the TPS was telling the ecu that the throttle was closed, but the MAP sensor which is downstream from the intercooler & plumbing (which are all full of air at start up) was telling the ecu that there was heaps of air because this stored air rushes into the plenum at start-up. The ECU would freak-out & put it into limp mode.

This setting is what keeps changing. If I write the tune file to the ecu it always starts at 2300 rpm on the first start, but after that it reverts back to 2500 rpm or higher. I have tried it at least 10 times now with the exact same outcome each time.

But I fixed it & moved on by making a vacuum operated air restrictor that works for 5 seconds at start-up, after 5 seconds it opens up to allow normal air flow again & the issue has gone. I just modified an old BA throttle body I had lying around and it works a treat. I did try an imported throttle body from China & it looked really schmick but after abut 100 kicks (starts) it leaked at the shaft.The throttle body on the left is the modded one.Here is a closer view of the restrictor

Last edited by BongoKongo on Tue Sep 06, 2016 7:46 pm, edited 1 time in total.

Yep, actually I haven't checked what rpm it reverts back to on a readout. I contacted the Tuner & he said it couldn't happen either. But I just went and disconnected the diverter & had another look. By the Tacho when its cold it revs heaps higher than 2500 it's reverting back to the standard Ford setting, it revs its nuts off. Once its hot it revs to about 2500 rpm but.Anyway I will just continue to use the previous tune & set the neutral rpm limit to 2500 & the diverter takes care of any excess air at start-up.I am going to experiment with a bigger Bypass valve on the blower to see if that helps too. I got a proper sprintex BPV that is New but has been sitting on a shelf for 6 years for less than half price still in the sealed bag it was born in..eBay can be Pus but sometimes it's a ripper.

Sounds like when cold it is using the cold start map which has different dash pot airflow, cam timing, fuel mixture and ignition timing which results in it revving higher. Is it noticeably different when warm vs cold?

Is this a ba/bf/fg ecu? If you can data log the cold start vs warm start I can tell you which map needs adjustment. Do you have an xcal and laptop?

Its a BA ecuyes I have laptop & xCal3 although the laptop hasn't been used in quite a while because its Sh*t. Might need to borrow a decent one to do this. I will get my brothers on the weekend and install the software & do a data log. I will pm u when I have it.Here is a photo of the Chinese throttle body I modded. I had to cut it in half, then design & weld up all of the linkages etc to suit, pity it leaked because it looked sweet. The new (BA Version) one works better but is not as appealing to the eye. O' well U get that sometimes.

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